Think about the moon revolving around the earth. This is circular motion. Gravity provides the centripetal force that causes the moon's circular round the earth. The moon is accelerating towards the earth, but never gets any closer to the earth. Why?

What would the difference of spectral lines emitted by hydrogen gas in distant galaxies which is normally found at a wavelength of 21 cm on earth, be observed at 21.1 centimeters?

Sarah and michelle work at a tech company that designs exercise apps. sarah tells michelle she has heard that james, their supervisor, interviewed with a competitor and may be leaving the company, which would open up a management position. what kind of power is sarah exerting?

The mass of the sun is 1.99×1030kg and its distance to the earth is 1.50×1011m. what is the gravitational force of the sun on the earth?